Universal joint assembly for an automotive driveline system

ABSTRACT

A driveline system for an automotive driveline system includes a transmission device, a differential device, and a universal joint having a drive shaft presenting terminal ends and interconnecting the transmission and differential devices. A yoke is connected to each of the terminal ends of the drive shaft and presents an internal surface and an external surface having generally equal thickness defined therebetween to form a dish of the yoke having a tubular monolithic structure. The yoke portion includes a bottom and a pair of spaced lugs each presenting sloping side walls for reinforcing the lugs as said yoke is rotated around a longitudinal axis.

RELATED APPLICATIONS

This is a divisional patent application of a non-provisional patentapplication Ser. No. 11/262,622 filed on Oct. 31, 2005, now U.S. Pat.No. 7,320,645 that claims the benefit of the provisional patentapplication Ser. Nos. 60/623,674 for a VEHICLE HAVING A UNIVERSAL JOINTDEVICE AND A PROCESS OF MAKING THE SAME, filed on Oct. 29, 2004 and60/636,190 for a UNIVERSAL JOINT ASSEMBLY FOR AN AUTOMOTIVE DRIVELINESYSTEM, filed on Dec. 15, 2004, which are hereby incorporated byreference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates generally to a driveline system for avehicle transmission. More particularly, the present invention relatesto a universal joint component of the driveline system and a method offorming the same.

2. Description of the Prior Art

A drive axle assembly of an automotive vehicle transmits torque from anengine and a transmission to drive vehicle wheels. The drive axleassembly changes the direction of the power flow, multiplies torque, andallows different speeds between the two of the drive wheels. The driveaxle assembly includes a plurality of components engaged in operativecommunication one with the other. One of these components is a universaljoint. Typically, the universal joint includes a pair of bifurcatedyokes or yoke portions, which are secured to drive shafts and which areinterconnected by a cruciform for rotation about independent axes. Thecruciform includes four orthogonal trunnions with each opposing pair ofaxially aligned trunnions mounted in a pair of aligned bores formed inthe bifurcated yokes.

Typically, a bearing cup is secured in each bore and a bearing assemblyis retained in the bearing cup such that each yoke is supported forpivotal movement relative to a pair of the trunnions. Variousconventional universal joints having yoke portions are known to thoseskilled in the vehicle driveline art and are widely used in theautomotive industry today. These universal joints are disclosed in U.S.Pat. Nos. 4,307,833 to Barnard; 5,601,377 to Ohya; 5,622,085 toKostrzewa; 5,845,394 to Abe et al.; 6,162,126 to Barrett et al.;6,280,335 to Wehner et al.; 6,336,868 to Kurecka et al.; 6,408,708 toSahr; 6,591,706 to Harer et al.; and 6,736,021 to Adams et al.

The U.S. Pat. No. 5,601,377 to Ohya, for example, teaches an automobilesteering column that transmits the rotation of the steering wheel to thesteering gearbox. For increasing the degree of freedom of geometricarrangement of the steering system, the steering column has a pluralityof steering shafts which are connected with each other by universaljoints. The universal joint, taught by the U.S. Pat. No. 5,601,377 toOhya, has a pair of conventional yokes and a cross member. Each yoke hasa base portion and a pair of arm portions or lugs opposed to each otherin a diametral direction of the yoke and extend in an axial direction ofthe yoke. Each arm portion has a circular opening and sides extending ina parallel relationship with the axial direction of the yoke. The yokeof the U.S. Pat. No. 5,601,377 to Ohya is taught to be connected to asteering shaft and is not subjected to numerous rotational movements as,for example, a yoke portion connected to a universal joint of adriveline and is, therefore, not considered as being feasible for use onthe driveline. In addition, the yoke does not include reinforcingfeatures of any kind to prevent bending of the arm portions duringrotation of the yoke.

The U.S. Pat. No. 5,845,394 to Abe et al., for example, teaches a methodof manufacturing a yoke portion having two spaced lugs for a universaljoint from a blank of a sheet metal to receive the yoke portion of auniform thickness. Similar to the yoke taught by the aforementioned U.S.Pat. No. 5,601,377 to Ohya, the spaced lugs are not reinforced toprovide structural integrity of the yoke portion. Again, the yokeportion is taught to be connected to a steering shaft and is notsubjected to numerous rotational movements as, for example, a yokeportion connected to a universal joint of a driveline and is, therefore,not considered as being feasible for use on the driveline.

To reduce the effect of vibration and the resulting noises,manufacturers have used various methods to construct drive shafts anduniversal joints connected thereto. Typical prior art yoke portions areiron cast to provide durability but are difficult to balance.

The opportunity exists for an improved universal joint and method ofmanufacturing the same that will reduce the mass of the yoke portionthereby reducing the effect of vibrations and the resulting noises, addstructural integrity to the universal joint, make it easier to balance,and increase performance of drive line applications at a low cost and ahigh volume.

BRIEF SUMMARY OF INVENTION

A differential assembly for an automotive driveline system includes atransmission device, a differential device, and at least one drive shaftthat extends between the transmission and differential devices. Thedrive shaft presents an operative communication with the transmissiondevice and the differential device. A universal joint device rotatesaround a longitudinal axis and presents operative communication with thetransmission device and the differential device. The universal jointdevice includes at least one yoke portion having a dish defining aninternal surface and an external surface. A generally equal thickness isdefined between the internal surface and the external surface of thedish to form a generally monolithic and tubular construction of the yokeportion. The dish is defined by a bottom and an annular wall integralwith the bottom. The annular wall extends to a pair of spaced lugsdiametrically disposed with respect to one another. Each lug extendsoutwardly to a head. Each lug presents a neck being wider in width thanthe head and sloping side walls interconnecting the head with the neckfor reinforcing the yoke portion as the yoke portion rotates around thelongitudinal axis. Each lug is reinforced by at least one indentation ordimple press formed in the lug in a shape of a gusset or a rib.

A connector extends between the yoke portion to mechanically engage atleast one of the transmission devices and the differential device toyoke portion thereby defining the aforementioned operativecommunication. The inventive yoke portion reduces vibration of theuniversal joint connected to the yoke portion of the generally equalthickness as the universal joint rotates about the longitudinal axis.

An advantage of the present invention is to provide an improved yokeportion for a universal join that is stamped from a sheet metalpresenting a light weight alternative to an iron cast yoke portion knownin the prior art, which reduces the effect of vibrations and theresulting noises.

Another advantage of the present invention is to provide an improvedyoke portion that reduces the mass of the improved yoke portion therebymaking it easier to balance and increase performance of the drivelineapplications at a low cost and a high volume.

Still another advantage of the present invention is to provide animproved yoke portion having a pair of spaced lugs and at least onegusset defined in each of the spaced lugs to provide structuralintegrity to the yoke portion that reduces the effect of vibrations andthe resulting noises and increases performance of the driveline systemat a low mass.

Still another advantage of the present invention is to provide animproved yoke portion wherein each spaced lug presents a central axisand sloping side walls inclined from the head to the neck therebyreducing stress applied to the yoke portion and preventing the spacedlugs from bending as the yoke portion rotates around the longitudinalaxis.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated asthe same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 shows an elevational view of a vehicle frame having a drivelinesystem;

FIG. 2 is an exploded view of a universal joint assembly;

FIG. 3 is a perspective view of a yoke portion of the universal jointassembly;

FIG. 4 is a cross sectional view of the yoke portion shown in FIG. 3;

FIG. 5 is an elevational view of the yoke portion shown in FIG. 3;

FIG. 6 is a side and partially cross sectional view of the yoke portionshown in FIG. 3 connected laser or spin welding to a drive shaft ofvarious diameters;

FIG. 7 an end view of the yoke portion shown in FIG. 6;

FIG. 8 is a perspective view of an alternative embodiment of the yokeportion of the universal joint assembly;

FIG. 9 is a cross sectional view of the yoke portion shown in FIG. 8;

FIG. 10 is an end view of the yoke portion shown in FIG. 8; and

FIG. 11 is a side and partially cross sectional view of the yoke portionshown in FIG. 8 mechanically connected to the drive shaft;

FIG. 12 is a top view of the progressive stamping stages of forming theyoke portion;

FIG. 13 is a cross sectional view of the yoke portion having an annularsleeve circumscribing an opening defined in spaced lugs of the yokeportion formed by a stamping process;

FIG. 14 is a fragmental perspective view of the yoke portion having theannular sleeve taken from the inner side of the yoke portion; and

FIG. 15 a cross sectional view of an alternative embodiment of the yokeportion having the spaced lugs of increased thickness formed by astamping process.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a chassis of an automotive vehicle, generally shownat 10, includes a frame 12 and a driveline mechanism. The drivelinemechanism includes a transmission assembly 14, a differential assembly16, and two universal joints, generally indicated at 18, extendingbetween the transmission assembly 14 and the differential assembly 16presenting an operative communication therebetween. The universal joint18 rotates around a longitudinal axis A during its operational mode. Theuniversal joint 18, as better illustrated in FIG. 2, includes a firstdrive shaft 19 and a second drive shaft 20 with a pair of yokes, suchas, for example a first yoke 24 and a second yoke 26. The first yoke 24is attached to the first drive shaft 19 and the second yoke or yokeportion 26 is attached to the second drive shaft 20.

A connector or cruciform assembly, generally shown at 28, interconnectsthe first yoke 24 and the second yoke 26. The cruciform assembly 28includes a cross member, generally indicated at 30, has a central hub 32and a pair of first trunnions 34 and 36 and a pair of second trunnions38 and 40. The first trunnions 34 and 36 are orthogonal with respect tothe second trunnions 38 and 40, with all of the trunnions 34, 36, 38,and 40 aligned within a common plane. The first trunnions 34 and 36 arecylindrical and are adapted for insertion into the first yoke 24.Similarly, the second trunnions 38 and 40 are cylindrical and areadapted to be inserted into the second yoke 26. The cruciform assembly28 and the first yoke 24 are known to those skilled in a differentialart and are not described and/or illustrated in great details.

Referring to FIGS. 3 through 7 the second yoke 26 is illustrated ingreat details showing a preferred embodiment of the present invention.The second yoke 26 is connected to each of the terminal ends of thesecond drive shaft 20 and presents an internal surface, generallyindicated at 42, and an external surface, generally indicated at 44. Thesecond yoke 26 presents a generally equal thickness defined between theinternal surface 42 and the external surface 44. A cup portion or a dish46 of the second yoke 26 includes a frustoconical configuration. The cupportion 46 has a bottom or base 50 defined by an upper annular wall 52.

A pair of spaced lugs 58 and 60 extend outwardly to a head 62, 64,respectively, from the annular wall 52. Sloping side walls 66 and 68interconnect each of the heads 62 and 64 with the annular wall 52 todefine a neck, generally indicated at 70, of each of the spaced lug 58and 60. Each sloping side wall 66 and 68 presents an acute angle definedbetween the axis A and each sloping side wall 66 and 68. Each of thespaced lugs 58 and 60 includes an opening 72. Preferably, the diameterof the opening 72 equals the distance defined between the opening 72 andthe bottom or base 50 of the cup portion 46. The spaced lugs 58 and 60are oriented diametrically with respect to one and the other. Each ofthe spaced lugs 58 and 60 includes an annular sleeve 74 integral withand circumscribing the opening 72. The annular sleeve 74 extendsoutwardly from the internal surface 42 of the second yoke 26. Theannular sleeve 74 presents a mechanical engagement with a pair of thefirst 34, 36 or second 38, 40 trunnions of the cruciform assembly 28 ina manner known to those skilled in the differential art. In addition,the annular sleeve 74 provides additional structural reinforcement forlocking the pair of the first 34, 36 or second 38, 40 trunnions of thecruciform assembly 28 within and between the spaced lugs 58 and 60.

A plurality of notches 78 and 80 are defined in the annular wall 52. Apair of oppositely spaced tabs 82 and 84 is defined between each of thenotches 78 and 80. Each of the spaced tabs 82 and 84 terminates in afolded lip portion 86 to strengthen the second yoke 26 in this area ofcut off. A pair of dimples 90 and 92 are formed in each of the spacedlugs 58 and 60. Each dimple 90 and 92 is concavely curved to define acavity as viewed from the external surface 44 of the yoke portion and abeveled configuration as viewed from the internal surface 42. Eachdimple 90 and 92 extends from each spaced lug 58 or 60 to the bottom orbase 50 the cup portion 46 with each of said dimples 90 and 92 formedbelow the annular sleeve 74. The dimples 90 and 92 are designed tostrengthen the spaced lugs 58 and 60.

Referring to FIG. 6, the yoke portion 26 is connected to the first driveshaft 19 or the second drive shaft 20 of various diameters, which mayvary from 3″ to 3.5″, respectively, by welding. Preferably, laserwelding is used to connect. Laser welding uses amplified light as thesource to produce the weld, i.e. specific wave length of light toaccomplish the welding process. As a high production welding process,laser welding produces deep penetration welds with minimum heateffective zones and has the advantage of welding dissimilar metals whileproducing very low heat. Laser welding is faster, cleaner, and more costeffective for manufacturing the inventive concept.

Alternatively, the yoke portion 26 and the drive shaft 19 or 20 may beconnected by spin or friction welding. Spin or friction welding usesheat generated by rotational friction at the joint line defined betweenthe yoke portion 26 the drive shaft 19 or 20 to weld them together. Amachine (not shown) applies pressure axially while rotating one of thepart, such as, for example, the yoke portion 26 against its stationarypositioned mate, such as, for example, the drive shaft 19 or 20, and theresulting friction generates heat that melts the parts together.Advantages of the spin welding process, used in the present invention,include high quality permanent joints, hermetic seals, lower equipmentcosts, ease of assembly, energy efficient operation, no ventilationrequired, immediate handling, entrapment of other parts, far-fieldwelding capability and no additional material requirements.

The second yoke 26 includes an alternative embodiment, generally shownat 100 in FIGS. 8 through 11. The second yoke 100 presents a generallyequal thickness defined between the internal surface, generallyindicated at 102, and the external surface, generally indicated at 104.A cup portion or dish 106 of the second yoke 100 includes afrustoconical configuration. The cup portion 106 has a bottom or basedefined by an annular wall 110 and forming the cup portion 106. A neck112 extends outwardly from the annular wall 110. The neck 112 has adiameter sized to receive the drive shaft 20.

As best shown in FIGS. 10 and 11, a plurality of circumferentiallyspaced female connectors 116 are defined in the neck 112 to mechanicallyengage the second drive shaft 20. A plurality of male connectors orprotuberances 118 are defined in the internal surface of the drive shaft20. The male connectors 118 of the drive shaft 20 mechanically engagethe female connectors 116 of the second yoke 100, thereby preventinglongitudinal and lateral movement of the second yoke 100 during rotationof the universal joint 18 about the longitudinal axis A, which reducesvibration of the universal joint 18 connected to the second yoke 100.

A pair of spaced lugs 120 and 122 extends outwardly from the cup portion106. Each of the spaced lugs 120 and 122 presents an opening 124. Thespaced lugs 120 and 122 are oriented diametrically with respect to oneand the other. Each of the spaced lugs 120 and 122 includes an annularsleeve 126 integral with and circumscribing the opening 124. Each of thespaced lugs 120 and 122 includes side walls 128 and 130 sloping relativethe longitudinal axis A. The dish 106 and each of the sloping side walls128 and 130 are interconnected by scalloped corners 131 and 133, asshown in FIGS. 8 and 10. Alternatively, the dish 106 and each of thesloping side walls 128 and 130 are interconnected by non-scallopedcorners, not illustrated in the present invention. The annular sleeve126 extends outwardly from the internal surface 102 of the second yoke100. The annular sleeve 126 presents a mechanical engagement with a pairof the first 34, 36 or second 38, 40 trunnions of the cruciform assembly28 in a manner known to those skilled in the differential art. Inaddition, the annular sleeve 126 provides additional structuralreinforcement for locking the pair of the first 34, 36 or second 38, 40trunnions of the cruciform assembly 28 within and between the spacedlugs 120 and 122. A plurality of notches 132 and 134 are defined in thecup portion 104.

A pair of oppositely spaced tabs 136 and 138 is defined between eachwith each notch 132 and 134. Each of the spaced tabs 136 and 138terminates in a folded lip portion 140 to strengthen the second yoke 100in this area of cut off. An indentation or muscle, generally indicatedat 142, is deformed in each of the spaced lugs 120 and 122 forstrengthening the spaced lugs 120 and 122. The muscle 142 is formed bystamping the external surface 104 of the second yoke 100 to form aconcavely curved cavity, which extends to a convexly curved portion ofthe gusset 142 as viewed from the internal surface 102. Preferably, thegusset 142 presents a triangular configuration as viewed from theexternal surface 104 of the second yoke 100 and a beveled triangularconfiguration as viewed from the internal surface 102.

The yoke portions 26 and 100 are formed by a progressive stamping,generally shown at 150 in FIG. 12, which is distinguished frommachining, the shaping of metal by removing material (drilling, sawing,milling, turning, grinding, etc.) and from casting, wherein metal in itsmolten state is poured into a mold, whose form it retains onsolidifying. The progressive stamping 150 is a metalworking process thatcan encompass punching, coining, bending and several other ways ofmodifying metal raw material, a strip of metal, generally indicated at152, as it unrolls from a coil (not shown), supplied by an automaticfeeding system (not shown). The automatic feeding system pushes thestrip of metal 152 in a progressive direction 154 through all of thestations or stages of the progressive stamping 150, as discussed furtherbelow. Each station performs one or more operations until a finishedpart, such as the yoke portion 26 or 100 is formed. These operations areperformed by a progressive stamping die (not shown). The progressivestamping die is placed into a reciprocating stamping press (not shown).As the reciprocating stamping press moves up, the progressive stampingdie opens. When the progressive stamping press moves down, theprogressive stamping die closes.

When the stamping press opens, the strip of metal 152 is feed therein bythe automatic feeding system pushes the strip of metal 152 in theprogressive direction 154, as best illustrated in FIG. 12. As thestamping press closes, the progressive stamping die performs work on theraw material.progressive stamping die, such as punching a contour 156 ofthe yoke portion, which includes the aforementioned spaced lugs and abottom of the yoke portion. As the progressive stamping 150 proceeds,the openings 72, 124 are punched out in each of the spaced lugs and thebottom of the yoke portion is stamped or deformed into theaforementioned dish. As the automatic feeding system pushes the strip ofmetal 152 in the progressive direction 154, the spaced lugs are bent toextend substantially perpendicular to the bottom of the yoke portion. Asthe strip of metal 152 is feed along the progressive direction 154 abutton member 160 is inserted between the spaced lugs to provide asupport for the spaced lugs as a pair of opposite die members 162 and164 are oriented to form the annular sleeves 74 or 126. The mechanicalaspects of the opposite die members 162 and 164 are known to thoseskilled in the stamping art. A pair of sliding mechanisms 166 and 168 ofthe respective opposite die members 162 and 164 terminated into a pressdie 170 and 172. The diameter of each press die 170 and 172 is largerthan the diameter of the openings 72, 124 to facilitate stamping of theannular sleeves 74, 126 as the sliding mechanisms 166 and 168 are movedtowards one and the other in the respective punching directions 172 and174 as the press dies 170 and 172 force the metal around the openings72, 124 into the annular sleeve 74 and 126. The final stage of theprogressive stamping 150 separates the finished part, i.e. the yokeportion 26 and 100 from a carrying web or link 178. The carrying web orlink 178, along with metal that is punched away in the previousoperations, is treated as scrap metal.

The yoke portion 26 and/or 100 are manufactured from a high strength lowallow steel manufactured by Worthington Steel Company. Preferably, acold bending process is used to manufacture the yoke portion 26. Ascompared to prior art heat treated of steel processes that leave carboncontent on the part, which prevents two part from being properly fusedin laser welding process, the cold bending is the most practical,accepted, and economical way to make large-radii bends and preservingstructural integrity of the part, such as, for example, the yoke portion26.

While the invention has been described with reference to an exemplaryembodiment, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A die formed yoke for a universal joint of an automotive drivelineassembly subject to the torsional loads of an automotive drivelineassembly having a substantially constant thickness, comprising: acup-shaped portion having an annular side wall; a pair of spaced opposedlugs integral with said annular side wall of said cup-shaped portioneach having opposed coaxially aligned annular sleeve portions extendingradially from said lugs; said annular side wall of said cup-shapedportion having an end portion including a plurality of spaced axialnotches; and a radial lip portion integral with and extending from anend portion of said annular side wall between said notches strengtheningsaid yoke.
 2. A die formed yoke for a universal joint of an automotivedriveline assembly subject to the torsional loads of an automotivedriveline assembly having a substantially constant thickness formed froma sheet of high strength low alloy steel, comprising: a cup-shapedportion having an annular side wall extending generally parallel to anaxis of rotation of said cup-shaped portions; a pair of spaced opposedlug portions integral with an end portion of said annular side wall ofsaid cup-shaped portion extending from an end of said annular side wall;a radial lip portion integral with and deformed outwardly from an upperend portion of said annular side wall between said lug portionsstrengthening said yoke; and said lugs each having an annular sleeveextending generally perpendicular to said lugs and coaxially aligned. 3.The die formed yoke as defined in claim 2, wherein said end portion ofsaid annular wall includes axial notches and said radial tab portionslocated between said notches.
 4. The die formed yoke as defined in claim2, wherein said annular side wall of said cup-shaped portion isfrusto-conical.
 5. The die formed yoke as defined in claim 2, whereinsaid lug portions each include a concave reinforcing dimple formedwithout increasing a thickness of said lugs.
 6. The die formed yoke asdefined in claim 5, wherein said dimples extend into an end portion ofsaid lugs adjacent said cup-shaped portion.